Income Taxes - Summary of Income Taxes (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2018	Jul. 31, 2017
Income Tax Disclosure [Abstract]
Income (loss) before income taxes	$ (5,950)	$ 5,529	$ (15,108)	$ 8,299
Provision for income taxes	$ 927	$ 2,226	$ 1,775	$ 2,432
Effective tax rate	(15.60%)	40.30%	(11.70%)	29.30%